Java Language Support 1.46+ breaks agent loading

Java Language Support 1.46+ breaks agent loading

For years I have been using a jar file that only contains the manifest file for a agent. This allowed for a fast convenient workflow cause I can make changes to the agent and quickly test them without the need of rebuilding the jar file.

The last version this worked is 1.45.0, after this it's broken.

The output you get after 1.45.0 is:

  /usr/bin/env /Library/Java/JavaVirtualMachines/jdk-24.0.2.jdk/Contents/Home/bin/java -agentlib:jdwp=transport=dt_socket,server=n,suspe
nd=y,address=localhost:62572 @/var/folders/hz/57zbqcy11q30rv9_gbdlvckc0000gn/T/cp_2neoah6v6lbyb5srzf0syfujp.argfile imgui_2026_examples.Example 
Exception in thread "main" java.lang.ClassNotFoundException: imgui_2026.UI_Widget_Agent
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
        at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:488)
        at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:556)
*** java.lang.instrument ASSERTION FAILED ***: "!errorOutstanding" with message Outstanding error when calling method in invokeJavaAgentMainMethod at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 627
*** java.lang.instrument ASSERTION FAILED ***: "success" with message invokeJavaAgentMainMethod failed at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 466
*** java.lang.instrument ASSERTION FAILED ***: "result" with message agent load/premain call failed at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 429
FATAL ERROR in native method: processing of -javaagent failed, processJavaStart failed
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.dylib+0x533e84]  jni_FatalError+0x7c
V  [libjvm.dylib+0x6a317c]  JvmtiExport::post_vm_initialized()+0x2cc
V  [libjvm.dylib+0x9dcc00]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x7a4
V  [libjvm.dylib+0x552dc8]  JNI_CreateJavaVM+0x74
C  [libjli.dylib+0xa438]  JavaMain+0x100
C  [libjli.dylib+0xd72c]  ThreadJavaMain+0xc
C  [libsystem_pthread.dylib+0x6c0c]  _pthread_start+0x88
zsh: abort      /usr/bin/env    imgui_2026_examples.Example

To Reproduce

Steps to reproduce the behavior:

I made a repository with a really small setup to reproduce.

1. download https://github.com/clankill3r/java_language_support_bug
2. run with 1.45.0 👍
3. run with 1.46.0+ 👎

Expected behavior

Instead of a ClassNotFoundException it should be able to run.

Environment

• Operating System: OSX 15.6
• JDK version: jdk-24.0.2
• Visual Studio Code version: 1.121.0
• Java extension version: 1.45.0 / 1.46+

从链接的 java_language_support_bug 仓库开始，使用提供的环境复现 Java Language Support 1.45.0 与 1.46.0+ 之间的差异。比较生成的启动参数或 classpath，以及 agent 加载行为；当 manifest-only agent 在受影响的版本中运行时不再出现 ClassNotFoundException，即视为完成。